1. Technical Field
The present invention relates to a collimator lens unit, an illuminating device, and a projector.
2. Related Art
Hitherto, a collimator lens unit including a first lens suppressing a spread angle of a beam of light emitted from a solid-state light source unit and a second lens substantially collimating the beam of light from the first lens has been known (for example, see JP-A-2005-208571).
Since the collimator lens unit substantially collimates the beam of light, the spread angle of which is suppressed by the first lens, by the use of the second lens, it is possible to efficiently substantially collimate the beam of light emitted from the solid-state light source unit.
On the other hand, a projector employing a white solid-state light source unit including a solid-state light source emitting main exciting light and a fluorescent layer converting and emitting the main exciting light has been known (see JP-A-2005-274957).
Since the projector includes the white solid-state light source unit of a small size and a small weight with small energy consumption, it is possible to construct a projector of a small size and a small weight with small energy consumption.
However, in the projector, the orientation distribution of the beam of light emitted from the solid-state light source unit exhibits a Lambert orientation distribution. Accordingly, when it is intended to apply the collimator lens unit to the projector, the luminous flux density in the vicinity of the optical axis of the collimator lens unit in the beam of light emitted from the collimator lens unit is lower than the luminous flux density in a peripheral portion separated from the optical axis of the collimator lens unit. For this reason, even when an integrator optical system for homogenizing the in-plane light intensity distribution of the beam of light emitted from the collimator lens unit is disposed at the rear stage, the ratio of light applied at a large angle to light applied to an illumination area increases. As a result, in a projector employing particularly a liquid crystal device having a micro lens built therein as an optical modulator, there is a problem in that the light use efficiency decreases due to the increase in ratio of the light applied at a large angle to the light applied to the illumination area.